The present invention relates to a phase change memory or a phase change recording medium, which is capable of recording/reproducing information by utilizing phase change.
In phase change recording method, recording is performed by unitizing a fact that material for a recording film undergoes phase change between crystal phase and amorphous phase and reading is performed by judging whether the recording film material is in the crystal phase or the amorphous phase, as disclosed in Applied Physics Vol. 71, No. 5 (2002) pp. 562–565, for example.
A chalcogenide, e.g. GeSbxTey, is representative recording film material in such phase change recording method, but its amorphous phase is unstable and sometimes crystallized with the lapse of time. This trouble becomes worse under circumstances of high temperature. Further, there is a problem that properties of the recording film material are degraded by repetition of rewriting in a case where volume change in the phase change between crystal phase and amorphous phase is large. It is desired to restrain such degradation to improve the reliability of the phase change memory.